A variety of nodes including a Web server, an application server and a DB (DataBase) server are set up in a data center where each of these nodes is usually made redundant to be prepared for an accident or a failure.
There is known a redundancy technique, for example, in which a primary node and a secondary node are provided as nodes in the data center so that, when the primary node fails, the secondary node instead takes over processing of the failed primary node and continues the processing.
There is also known a technique in which a secondary data center provided as a backup of a primary data center takes over processing executed in the primary data center and continues the processing, when the primary data center is damaged.
Patent Literature 1: Japanese Laid-open Patent Publication No. 2008-134986
When the secondary data center takes over the processing as a substitution for the primary data center, a data lost incidental to the switchover of the data center needs to be prevented. The switchover to the secondary data center is needed for different reasons at different times and, in a mode where switchover control is executed in the same way regardless of the reason for the switchover, more data lost may possibly occur.